Relentless Logic is an early computer game often credited1 as the inspiration for Windows Minesweeper. The object of the game is to move your Marine from the top left corner of the screen to the Command Center at the lower right corner, without stepping on a mine:

You are a private in the U.S. Marine Corps. You have been selected by the Base Commander to perform a noble task. The future of the United States rests in your hands.

Communications are down. You have been instructed to deliver an important message to the U.S. Command Center. Between you and the Center is a field teeming with hidden land mines.

You have two tools at your disposal. One is a mine detector. It will tell you how many mines are hidden in squares surrounding you. You also have one of the most important attributes known to man ... RELENTLESS LOGIC. With this gift and the clues given to you by the mine detector, you should be able to accomplish the mission without blowing yourself to bits ... maybe. Anyways you’re our only hope.

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The game is monochrome and takes place on a 15x9 grid of squares. At the start of each game you have the option of placing from 10 to 40 mines on the field. The only input allowed is your keyboard, and directions are given using the number pad. After each move the game tells you how many mines touch your current location, and you use this information to navigate safely. There are no hints or numbers on the grid. You may only move to adjacent squares and it is not possible to mark mine locations. The game keeps track of how many moves you make, and after each move it updates the timer. The goal is to safely reach the command center in the fewest moves and least amount of time.

When you lose, the field explodes and you are told “You stepped on a mine ... and you let America down.” This explosion only occurs the first time you lose after the program is opened. If you win, the game states “You took X moves to save America...Thanks” and it gives you a skill rating. There is no highscore list, so you must remember your best scores. Music plays at the start and end of each game.

Relentless Logic is written by ‘Conway, Hong and Smith’, although one early clone mysteriously thanks ‘Conway, Wayne and Chung’2. The earliest proven date for its existence is 9th November 1985, when a user uploaded RLogic.exe to the ‘Fargo IBM PC Users Group’ bulletin board system in North Dakota. This BBS was hosted by Loren Jones, who relocated the system to Chicago in 1987. In 1989 he started collecting files on his system into a CD which became known as ‘RBBS-in-a-Box’. Several collections were made, and the final release on 11th June 1991 contained more than 15000 games and programs. As of writing, version 3.1 is still available for download on two sites dedicated to preserving BBS history. The game gives no information about its origins other than the name of its authors.

According to Tom Kelsh3, who began working at IBM in 1985, RLogic was popular among the programmers there for a short time. Tom Anderson4 witnessed colleagues at Fluke Manufacturing playing RLogic at work on computers running DOS in 1987.

1. Wikipedia and various websites.
2. Game instructions for Landmine (1988), written by Larry Ludwick.
3. Personal correspondence with author. Tom Kelsh is on the Minesweeper World Ranking.
4. Discussion page for ‘Minesweeper Game’ at Wikipedia.